2026 ICD-10-CM Diagnosis Code B25.0Cytomegaloviral pneumonitis

ICD-10-CM Codes›A00–B99›B25-B34›B25

ICD-10-CM B25.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B25.0 is a billable ICD-10-CM diagnosis code for cytomegaloviral pneumonitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 177 through 179. Coders also document this condition as cytomegaloviral pneumonia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pneumonia (except that caused by tuberculosis) and Viral infection.

Code Identity

ICD-10-CM Code
B25.0
Billable Status
Yes — Valid for Submission
Code Describes
Cytomegaloviral pneumonitis
Short Description
Cytomegaloviral pneumonitis
Same as the full description in the CMS dataset.
Parent Code
B25
Cytomegaloviral disease

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB25-B34Other viral diseases
CategoryB25Cytomegaloviral disease
This CodeB25.0Cytomegaloviral pneumonitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cytomegaloviral pneumonia

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disease, diseased
      • cytomegalic inclusion (generalized)
        • with pneumonia
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • cytomegalic inclusion
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • cytomegaloviral
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • in (due to)
        • cytomegalovirus disease

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR RSP002
Pneumonia (except that caused by tuberculosis)
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF008
Viral infection
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Cytomegalovirus Infections

Cytomegalovirus (CMV) is a virus found around the world. It is related to the viruses that cause chickenpox and infectious mononucleosis (mono). Between 50% and 80% of adults in the United States have had a CMV infection by age 40. Once CMV is in a person's body, it stays there for life.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B25.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
078.5 Cytomegaloviral disease
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
484.1 Pneum w cytomeg incl dis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About B25.0Overview

Is B25.0 (Cytomegaloviral disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cytomegaloviral pneumonitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B25.0 group to?

When cytomegaloviral pneumonitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 177, 178, 179, with relative weights from 0.7550 to 1.5627 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B25.0?

Under the General Equivalence Mappings, cytomegaloviral pneumonitis converts to ICD-9-CM 078.5 (cytomegaloviral disease) and 484.1 (pneum w cytomeg incl dis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.